Green Design - Solar Energy

solar energy

Solar Energy

We have a free greatest source of energy - the sun. Maximizing use of solar energy is integral part of green design. While using solar energy to its fullest requires comprehensive design of the building structure, you can gain significantly from relatively minor building work or decorating strategies. In most homes, the sun can provide up to about 10 percent of your warmth requirements, depending upon the building's orientation, setting, and construction. There are a lot of things you can do to capture the sun and increase your home energy conservation.

Windows are the prime source of natural light in your house. They connect you to nature, drawing earth s energy into your spaces, magnifying your spiritual energy. Today's more open style of architecture that incorporates more windows, generally larger, as well as skylights that add considerable light and life to interior space, is transforming houses from dark, dull shelters to homes shimmering and humming with vitality. This is a positive trend that hopefully continues in the decoration of houses.

Skylights (windows placed in the ceiling) may be single or grouped panels of clear of translucent glass or plastic, either flat or domed, and fixed or movable for ventilation. Skylights in kitchens, laundries, and bathrooms have the special advantage of providing adequate daylight for inside rooms. In small areas light from above can expand visual space and make the sky and trees part of a room. The skylight window has a number of disadvantages, however, including problems with water seepage, insulation, and cleaning. Skylights can be of various sizes and shapes and may be movable, stationary, or combinations of both types.

Anyone with a window that lets in direct sunlight knows how much heat can be generated through the glass (this is known as solar gain). The challenge is to capture and store this warmth for as long as possible after the sun has set. Dark, heavy materials such as concrete, stone, or tiles absorb and store heat, then radiate it back into the space when the outside temperature drops. To make best use of this in rooms with a sunny orientation, use materials such as slate, dark ceramic tiles or even dark, painted concrete on floors, work surfaces, and other flat areas (see also: green flooring materials).

energy-efficient windows

Free Heat From The Sun

Some windows can save energy without being bulky and heavy. Manufacturers are making glazed windows with a transparent, non-glare coating on the inside layers to help slow the transmission of heat energy through glass. Such windows are made with low-E (low emissivity) coatings. They help interior environments stay more comfortable.

Low-E glass treats sunlight's different wavelengths in different ways. The sun's energy spectrum is divided into three ranges of wavelengths: ultraviolet, visible light, and infrared, which can be felt as heat. (These heat-generating infrared rays are further divided into long wavelengths and short wave-lengths.) The challenge is to let in visible light and control infrared transmittance.

Low-E glass, with its low-emissivity pyrolytic coating, lets in approximately 95 percent as much visible light as ordinary insulated glass, allowing the interior to look bright and the window to appear transparent. However, low-E glass reflects most of the long-wave infrared energy back toward its source, helping to keep summer heat out and winter heat.

Performance can be even better with the addition of argon gas (a super insulator) between the layers of glass in the window unit. As a result of these new energy-efficient developments, windows can be practical as well as beautiful.

The larger the area of glass, the more southerly the orientation, and the larger the absorbent surface, the greater the capacity to store and re-radiate heat. This idea must, of course, be balanced with the desire to have light surfaces near windows to reflect light and increase brightness. With some construction work, it is possible to enlarge windows, add a bay, or make a sun-porch, all of which collect solar gain. The larger the amount of external wall these devices can cover, the better, but bear in mind that any large windowed areas must be made of insulating glass. Solar panels, of course, are the most effective way of making use of solar gain and can substantially reduce energy costs. Solar buildings are built to capture the sun's energy and conserve conventional fuel.

The Passive Solar System

The passive solar system is a non-mechanical method relying on the building itself to absorb and store the sun's heat. (Note: All compass directions are given relative to the northern hemisphere; for southern hemisphere applications, substitute north for south.)

- Buildings are space planned so that frequently used spaces are oh the south side.

- Windows are generally limited to the south wall, with occasional east and west wall use.

- The north side of the building is slightly bermed, or buried under dirt.

- Evergreen trees are planted to the northwest of the building to block cold winter winds.

- Deciduous trees (those that lose their leaves in winter) are placed to the south to block the hot summer sun, yet allow winter sun to reach the building.

- Overhanging eaves are designed in accordance with the angle of the sun to allow winter sun to enter a building, while blocking summer sun.

- Thermal storage units, such as masonry walls, fireplaces, stone floors, or large water containers (such as an indoor pool), are located to absorb solar energy during the day. At night the stored it heat is released into the building.

- If exterior doors enter into small passageways that serve as an air lock.

- Highly efficient stoves may function as auxiliary heating devices.

- In the summer, lower windows may be opened to draw in cooler air, while skylights, ceiling fans, and upper windows are used to draw the warmer air up and out of the building.

- Low-growing vines and shrubs are planted on the south side of the building to prevent glare.

active solar system

The Active Solar System

The active solar system relies on mechanical means - photovoltaic (or solar) panels, fans, and pumps - in addition to the principles of passive solar design to trap and use energy from the sun.

Active solar systems can also provide electricity for the building. Photovoltaic panels convert sunlight into DC electricity, which is stored in a series of batteries. An inverter changes the electricity from DC to AC, the type used in conventional building designs. Batteries are generally housed in a utility room with a small vent to the outside for gases to escape.

A solar batch water heater can be used in sunbelt areas. This type of water heater provides hot water by mid-morning on sunny days, and keeps it hot until well after subset.